From: Gleb Natapov <gleb@redhat.com>
To: Jan Kiszka <jan.kiszka@web.de>
Cc: qemu-devel <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] Re: [PATCH] hpet: Clean up initial hpet counter
Date: Thu, 17 Jun 2010 11:36:16 +0300 [thread overview]
Message-ID: <20100617083616.GL523@redhat.com> (raw)
In-Reply-To: <4C19DD17.3000408@web.de>
On Thu, Jun 17, 2010 at 10:30:15AM +0200, Jan Kiszka wrote:
> > Sorry, I lost you here. What "works for IO-based fw-cfg, but not for
> > MMIO-based".
>
> Undefined IO ports return -1, undefined (/wrt read access) MMIO 0. So
> you need to select a key that is different from both.
>
But can we rely on it? Is this defined somewhere or if it happens to be
the case in current qemu for x86 arch.
> > Can you write pseudo logic of how you think it
> > all should work?
>
> The firmware should do this:
>
> write(CTL_BASE, FW_CFG_ID);
> if (read(CTL_BASE) != FW_CFG_ID)
> deal_with_old_qemu();
> else
> check_for_supported_keys();
>
Ah, I thought about read() returning 0/1, not key itself, so any key that
always existed would do.
--
Gleb.
next prev parent reply other threads:[~2010-06-17 8:36 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-15 22:40 [Qemu-devel] [PATCH] hpet: Clean up initial hpet counter Jan Kiszka
2010-06-16 4:40 ` [Qemu-devel] " Gleb Natapov
2010-06-16 7:03 ` Jan Kiszka
2010-06-16 7:33 ` Gleb Natapov
2010-06-16 7:51 ` Jan Kiszka
2010-06-16 7:52 ` Gleb Natapov
2010-06-16 7:57 ` Jan Kiszka
2010-06-16 9:06 ` Gleb Natapov
2010-06-16 9:33 ` Jan Kiszka
2010-06-16 9:35 ` Gleb Natapov
2010-06-16 15:36 ` Gleb Natapov
2010-06-16 16:00 ` Jan Kiszka
2010-06-17 5:48 ` Gleb Natapov
2010-06-17 7:17 ` Jan Kiszka
2010-06-17 8:07 ` Gleb Natapov
2010-06-17 8:30 ` Jan Kiszka
2010-06-17 8:36 ` Gleb Natapov [this message]
2010-06-17 8:42 ` Jan Kiszka
2010-06-17 8:46 ` Gleb Natapov
2010-06-17 8:59 ` Jan Kiszka
2010-06-17 9:01 ` Gleb Natapov
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